Governing mechanism



Jan.'19 1932. H. SCHMIDT 1,841,424

GOVERNING MEGHANI SM Filed July 26, 1929 WITNESS INVENTOR ATTORNEYPatented Jan. 19; 1932 IUNITEKD":

HENRY F. SCHMIDT; o r'nansnow m, rENNsYnvA'nrA; Assreuonuo wnsrineirousrELECTRIC & MANUFACTURING COMPANY, A oonronazrrou' or rruusrnvaura jGOVERNING M cnANIsM Application filed July '26, 1929.- Serial No.381,374.

My invention relates to a fluid pressure govern ngmechanism, and it hasfor an object to provide a mechanism of the character set forth havingimproved operation.

According to one form of fluid pressure governing mechanism, describedand claimed in the patent of A. T. Kasley, N0; 1,73 2,812,1

filed October 22, 1929, fluid pressure varying as a function of the,prime mover to be gov erned is provided by a centrifugal pump driven bythe prime mover. This fluid pres-3 sure is imposed on apressure-responsiveelement on which is also imposed,'in'opposition? tosaid pressure, a fluid pressure provided: in an enclosed spaced byadmitting a restricted;- fiow of fluid under pressure and controllingtheescape of fluid fromthe space by a pressure-relief valve. The settingof the governing mechanism is changed by varying the setting of thepressure-relief valve',zwhich therefore constitutes the speed changermechanism. 1 Inasmuch as the fluid pressure .de

livered by the pump is the pressure developed} by the impeller increasedby thespressureat which fluid is supplied'tothe pump,.such a governingsystem is subjected to anylvaria tions in the pressure at whichfluid iswsupe plied to the pump.

It is a more particular object of my inven-Z tion, therefore, toeliminate the-eflect on the pressure-responsive.-element of variationsin pressure at which fluid is supplied to the pump.- r

In accordance with my the pressure of the fluid supplied to the pump.Thus the pressurein the, enclosed space is in creased by the sameamount. Sincethe-variations in the pumpsupply pressure thus equal- .lyaffect the fluid pressures on opposite sides.

of the pressure-responsive element, the effect thereof on said elementis eliminated;

The above and other'objects are efl'ectedby' my invention, as will beapparent from'the following description and claims takenin. connectionwith the accompanying drawing,

being shown in section.

invention,- the re lief valve is sub ected'mclos1ng 'dlI'BCtlOIl to,

Referring now to the drawings more inde tail, I showa valve'lO forcontrolling the admission of motive fluid-to a :prime moveip:

The governing mechanism for controlling the same includes acentrifugalpump, 11'; having an impeller l2 mounted" on the shaft 13ofthe primefmover to be governed. Fluid issupplied through a conduit-14to the inlet cham-;

ber 15 of the pump at a positive pressure, by an ejectorgl'fi. Thelatter is motivated by fluid pressure dischargedfrom the pump 11,.

and 'entrains fluid flowing by gravit yfrom a therewith; The relayniechanisniincl l1$a casing 19 1havinga cylinder .Zl fOrmed'there-Q" v AQaer'at s. P t QZZ; ce d a f valve 10 byymeansiof a stem 20,isdispjosed: in the cylinder 21 and valvelO bysprings 23.

is biased to cl L The relay mechanism f r pilotva-lve24, disposed-in asleeve 25 fixedlin: the casing 19. The sleeve25 has ports 26 and 27.communicating with the upperand lower. ends, respectively, of thecylinder 21. g.It;is,

further provided with; inlet ports 28,,com5; municating with a chamber29 formedinthe casing. 19 to which fluid under pressure is;admitted-through an opening 30w It is also providediwith;discharge;ports 31 and325 communicating with a discharge chamber 33 in. the casingfrom whiehfluid is discharged through an 'opening34.;l g p' 'z The-pilotvalve 24 is formed with -piston portions 35and 3.6, which cover the'portsQfi and 27;.respectively-, in normal or cut-off DO-.1 i A siti'onof-the-pilot valve. The latter isfurtherprovided with piston portions 37and'j38 atthe upper andlower ends thereof, respec-' tively. I r :1 .1The pilot valve is formed with. a hollowirrterior and a closed upperend." It is connected at its upper end to the upper endof a spring 39disposed within the interiorthereof. The.

lowerend of the spring is connected to the upper end of astem 41.extending througlr the casing and connectedatits lower endto a lever 42intermediate the ends of the latter. The lever 42 is pivotally connectedat one end to the stem 20 and at its other end to a stationary fulcrum43.

The pilot valve 24 is also the pressure-responsive element of thepresent construction. Fluid pressure delivered by the pump 11 isconveyed through a conduit to the lower end of the sleeve 25 and biasesthe pilot valve upwardly in opposition to the force of the spring 39.The upper end oithe sleeve opens into a chamber 45 in the casing, intowhich a restricted flow of fluid is provided, as by an orifice 46 in theclosed end of the pilot. valve.

The chamber 45 is provided with a discharge opening 47, controlled byrelief valve 482, which is biased to. closed position by a spring 49 andwhich thereby imposes a pressure onthe fluid in the chamber 45. Theupper end of the spring 49 abuts against a movable spring-holding member51, controlled by a lever 52, by means of which the spring deflection,and thus the fluid pressure in the chamber 45, may be varied.

The relief valve 48 is disposed in a cham ber into which flows'thc fluidwhich escapes through the opening-47 from the chamber 45. The chamber523 communicates with the conduit 14 by means of a conduit 54. The

fluid flowing into the chamber 53 is thereby returned to the pump inletchamber 15', and

the pressure of the fluid insaid pump inlet' chamber andv the pumpsupply conduit 14 isthus maintained in the chamber 53.

? Thefluid pressure in the chamber 53 is imposed on the relief valve 48,biasing the.

same in closing direction The pump inlet pressure is thus imposed on thefluid inthe chamber 45, in addition to the pressure imposed by' theforce ofthe spring: 49 on the relief valve. i

The chamber 45 is adapted to communicate with a drain chamber 55 throughan opening, 56 controlled by a valve; 57. The latter is connected to apiston 58 which issubj'ected to the pump inlet pressure, communicated tothe chamber 59 from the chamber 53 through a'passage 61. The piston isbiased in opposition to the fluid pressure by a spring 62 with such aforce that when-the pump inlet pressure decreases below a predetermlnedpressure, the piston moves; the valve 57 to uncover the opening 56', andthe fluid pressure in the chamber 45 is released.

The operation of the above-described embodimentwis as follows: r Thepilot valve 24 is biased upwardly by the fluid pressure delivered by thepump 11. This fluid pressure is opposed by the fluid pressure in thechamber 45, and the excess or resultant fluid pressure moves the pilotvalve upwardly to deflectthe tension spring 39. Upon increase in speedof the prime mover, the increased pump pressure efl'ects upward movementof the pilot valve and increased deflection of the spring 89. As will beapparent from the drawing, the ports 26 and 28 will be placed incommunication, as will also the ports 27 and 32. Fluid under pressurefrom the chamber 29 is thus supplied to the upper end of the cylinder21, and the fluid'in the lower end thereof is discharged to the chamber33. The piston 22 is moved downwardly to efiect decreased opening of theadmission valve 10, until the pilot valve is restored to cut-oilposition the stem 20 through the. link 42, the stem 41 and the spring39.

"Upon decrease in speed, the fluid pressure is decreased, and the pilotvalve 24 is moved downwardly by the spring 39! The relay mechanism thenoperates in the reverse manner to effect increasedope-ning of the admission valve 10.

The variations in pressure of the fluid supplied to the pump at itsinlet affect the pre. sure of the fluid delivered by the pump in likemanner. For example, if the pressure of the fluid supplied to the inletchamber by the ejector 16 increases by one pound per square inch, due tochange in viscosity or to one of several other causes,'the fluidpressure in the lower end of the sleeve 25 is also increased by onepound per square inch. However, the fluid pressure in the chamber 53 isincreased by that amount, and hence'th-e pressure in the chamber 45 islikewise increased by one pound per sr uare'iuc ,thns offsetting theincreased pressurebel'ow the pilot valve. Thus the pilot'valve 24 isentirely unaffected by the variations in the'pump supply pressure, andthe governing action of the governing neclr anism as a whole is likewisenot affected by suchvariations. p r

The'pressure-relief valve 48 and the means for varying the spring forcethereon constitute the speedchanger mechanism. By increasing thecompression of'tlie spring 49, the fluid pressure in the chamber 45 isin creased, which means that a higher speed of the shaft 13 is requiredto provide suhicien; fluid pressure'beneath the p lot valve 24 to opposethe increased pressure in said chamber, and to bring the same to cut-offposition. By decreasing the spring compression, the speed, setting islowered, as will be apparent.

It is tobe' noted that the pressure in the chamber 45 is equal to thesum of the fluid pressure in the chamber 53 plus the force of the spring49 on the valve 48. Thus the fluid pressure in the chamber 553 modifiesthe action ot' the speed changer mechanism only to eliminate the ellecton the pilot valve of variations in pump inlet pressure, and theoperation of the speed changer mechanism in changing the speed settingof the governingz mechanism is not aiiected.

Should the pump, inlet pressure decrease to such an extent as toindicate an abnormal condition of the fluid pressure system, the

ranges;

valve' 57 releases the fluid pressure in the chamber 45, as describedabove. The resultant or effective fluid pressure biasing the pilot valve24 upwardly is thus increased by the'amount of this pressure, and theupward movement of the pilot valve efl'ects closing of theadmissionvalve 10. 'This part of the mechanism is not part of thepresent invention, but is described and claimed in an application of O.N. Bryant and A. F. Schwendner, Serial No. 850,608, filed March 28,1929.

lVhile I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various changes and modifications without departing from the spiritthereof,

and I desire, therefore, that only such limitations shall be placedthereupon as are imposed by the prior art or as are specifically setforth in the appended claims.

lVhat I claim is:

1. In a fluid pressure governing mechanism for a prime mover, thecombination of a pump developing fluid pressure varying with the speedof the prime mover, means for supplying fluid at a positive pressure tothe inlet of said pump, a presslueresponsive element subjected in onedirection to the fluid pressure delivered by said pump, means controlledby the pressure-responsive element for controlling the prime mover,means providing an enclosed space, the pressure-responsive element beingsubj ectcd in the opposite direction to the fluid pressure therein,means providing a restricted flow of fluid under pressure into saidspace, a pressure-relief valve controlling the fluid pressure therein,and means for subjecting the pressure-relief valve in closing directionto the fluid pressure at the inlet ofthe pump, whereby variations insaid pump inlet pressure are transmitted to the fluid pressure in theenclosed space to compensate for similar variations in the fluidpressure delivered by the pump. a

2. In a fluid pressure governing mechanism for a prime mover, thecombination of means providing a fluid pressure varying with the speedof the prime mover, means for supplying fluid under positive pressure tothe inlet of said means, a pressure-responsive element subjected in onedirection. to the fluid pressure delivered by the first-mentioned means,means controlled by the pressure-responsive element for controlling theprime mover, means pro viding an enclosed space, the pressure-responsiveelement being subjected in the opposite direction to the fluid pressuretherein, means providing and controlling a fluid pressure 111- saidspace, and means for modifying the ac tion of the last-mentioned meansin response to variations in the fluid pressure at said inlet, wherebysaid variations are transmitted to the fluid pressure in said enclosedspace to compensate for similar variations in the fluid pressuredelivered the first-mentioned means. H s r a p 3; 1 In a fli11(:l',pre'ssure governing mechanism for a prime mover, the combinationof a centri fugal pump developing fluid pressure vary ng F lth the speedof the prime mover, means foi'tsupplyiug fluid at a positivepressurefto. the inlet 1 of the i 1. 1 mp, a pressure-r -j sponsiveelement subjected to the fluid pressure-delivered by saidpump, meanscon-' trolled by the pressure-responsive elementfor controlling theprimemov'er',means for subjectin'g the pressure-responsive element to asecond fluid pressure and for'controlling said pressure,"and; means formodifying the action of the last mentione d'ineans in responseto fvariations in the pump" inlet pressure to compensate-for similarvariations in the fluid pressure delivered by the pump.

a 4. In a fluid pressure'governing mechanism for a primemoverythefcombination of acentrifugal' pum p developing fluid pressureva' rying with the speed of the prime mover;

means'for supplying fluid at a positive pressure to the inlet-ofthepump. a pressure responsive elem'ents'ubjected 'to the fluidpressuredeliveredbysaid-pump, means controlled by the pressure-responsive elementforfconw trolling the primemover,':'mean's for subjectting thepressure-responsive element to a sec- 0nd fluidi'pressure and'forcontrolling said a pressure, means for varying the setting 0t I Isaid pressure control meansto vary the speed setting otfifthe-governmgmechanism, and

means formodifying' thef action of the pres-v sure .control' 'mea ns"without changing said settingfin response to variations in the pumpinlet pressure to compensate for s1milar'va-1 riations inthefluidpressure deliveredbythe Pu 1 l 5. In a fluid pressure governingmechanism for controlling-a prime mover"in resure varying withthe aspeedof the prime mover, a pressure-responsive element subjected tosaid fluidpressure,-means controlled by the pressure r esponsiveelement forregulating the admission of motivefluid to the prime mover, meanstorsubjecting the pressure responsive element to a second fluid pressure,means for controlling the second fluid pressure, means for applying a"third, fluid pressure to the last-mentioned means ment subjected to avariable fluid pressure,

means for subjecting the pressure-responsive element to asecond fluidpressure, means'for ies sponse to thre'e variabl'efluidpressures, thecombination of means providinga fluid prescontrolling the second fluid,pressure,-means for applying a third fluid pressure to the last-namedmeans to inodifyflthe action thereof whereby the variationsin the thirdfluid pressure are transmitted to the second fluid pressure andimposedon the pressureresponsive element, and means controlled bythe1pressure-responsive element for controlling the operated member.

- 7. In a fluid pressure regulating mecha nism for controlling anoperated .member in response to three variable fluid pressures, thecombination of a pressure-responsive element subjected to a, variablefluid pressure, means for subjecting the pressure-responsive element toa second fluid pressnre, means for controlling the second fluidpressure, means for varying the setting of said pressure control meansto vary the settingof the regulating mechanism, means for imposing. athird fluid pressure on the pressure controlmeans tomodify the actionthereof Without changing said setting whereby the variations inthe thirdfluid pressure'are transmitted'l to the second fluid pressure andimposed; on the pressure-responsive element, and means controlled by thepressure-responsive element for controlhngthe operated member.

,8.;In a fluid pressure regulating mechanism for controlling anoperated'member in response to three variable fluid pressures, thecombination of a pressure-responsive element subjected to a v variablefluid pressure, means providing an enclosed space, means providing arestricted flow of fluid into said space, a pressure-relief valvecontrolling the escape of fluid from said space and the fluid pressuretherein, means for imposing a third fluid pressureupon thepressure-relief valve whereby the fluid pressure in said space issubjected tothe variations in the third fluid pressure,, saidpressure-reponsive element being also subjected tothe-fluid pressure insaid space, and means-controlled by the pressure-responsive element forcontrolling the operated member. 1

In testimony whereof, ii-have hereunto subscribed my name this 24th dayof July, 1929. V .j 1 'f i HENRY F. SCHMIDT.-

